Process for the production of n-acylamido diols



Patented Oct. 26, 1954 UNITED STATES PATENT OFFICE PROCESS FOR THE PRODUCTION OF N -ACYLA1VHDO DIOLS Harry M. Crooks, Jr., Detroit, Mich assignor to Parke, Davis & Company, Detroit, Mich., a. corporation of Michigan No Drawing. Application August 22, 1951, Serial No. 243,167

H OH NH-O-CHOlz Both the starting materials and products of the process exist in structural as well as optical isomeric forms. The term structural refers to the spatial relationship of the polar groups attached to the two asymmetric carbon atoms. In order to differentiate between these structural or diastereoisomeric forms they will subsequent- 1y be referred to as the threo and erythro" forms in accordance with the accepted nomenclature for this type of product.

Both the threo and erythro forms exist in optically racemic as well as optically active forms. Because of the difiiculty of graphically representing the difierent structural and optical forms the customary graphic formulas will be used and a designation placed below or to the side of the formula to designate the particular structural and optical configuration of the compound. It should be expressly understood that where no notation appears with a structural formula the formula is to be interpreted in its generic sense, that is, as representing the D-threo, L-threo, D-erythro and L-erythro in separated form as well as the DL-threo and DL-erythro optical racemates and the total unresolved mixture of structural and optical isomers. Such a formula does not merely represent the unresolved mixture of isomers.

In accordance with the invention, l-p-nitrophenyl 2 dichloroacetamido 1,3 propanediols having the above formula are produced by reacting a l-p-nitrophenyl-Z-amino-1,S-propanediol of formula,

OH NHz i NOz-QlEb-CH-CHMH 9 Claims. (01. 260-562) ents such as alkyl, alkoxy, halogen and nitro groups and the like. Some specific examples of such N -acylated dichloroacetamides are N-acetyl dichloroacetamide, N dichloroacetyl dichloroacetamide, N -benzoyl dichloroacetamide, N-propionyl dichloroacetamide, N-methoxyacetyl dichloroacetamide, N p methylbenzoyl dichloroacetamide, N-p-nitrobenzoyl dichloroacetamide,

N p methoxybenzoyl dichloroacetamide, N -0-- bromobenzoyl dichloroacetamide and the like.

In carrying out the process alcoholic, aqueous or aqueous alcoholic solvents may be used. For example, water, aqueous methanol, aqueous ethanol, aqueous isopropanol, methanol, ethanol, isopropanol, n-propanol, butanol and the like can be employed.

The relative quantities of the reactants is not particularly critical but for economic reasons it is customary to employ either approximately equimolar amounts of the two reactants or a slight excess of the dichloroacetamicle or N- acylated dichloroacetamide.

the reaction proceeds so rapidly that the reaction mixture does not need to be heated. However, when dichloroacetamide is used as the acylating agent, the reaction mixture should be heated to bring about the reaction within a reasonable time. In general, the reaction mixture should not be heated above about 100 C. because higher temperatures bring about considerable decomposition of the amino diol starting material. Best results are obtained using a temperature in the neighborhood of 50 to C. In the case of dichloroacetamide the use of a basic catalyst such as an alkali metal alkoxide or an alkali metal carbonate also increases the yield and reduces the reaction time. The temperature is not critical when using the N-aoylated dichloroacetamides because the reaction proceeds so rapidly that in most cases the amino diol starting material is completely converted into the heat-stable acylamido diol before the reaction mixture can be even heated to C. This being the case, there is no necessity for employing temperatures in excess of 100 C. in conjunction with the N-acylated dichloroacetamides.

The products produced by the process of the invention find use as antibiotics or as chemical intermediates for the production of other organic compounds possessing antibiotic activity. For example, the product of Example 1, D- -threol p nitrophenyl 2 dichloroacetamido 1,3- diol, which is commonly known as chloramphenicol is of particular value in the treatment When using an N-' acylated dichloroacetamide as the acylating agent of typhoid fever, typhus, urinary tract infections, gonorrhea and many other diseases and conditions.

The invention is illustrated by the following examples:

Example 1 A solution consisting of 2.5 g. of N-dichloroacetyl dichloroacetamide and 2.1 g. of D-(-)- threo 1 p nitrophenyl 2 amino 1,3 propanediol in 20 cc. of methanol is heated for five minutes at 65 C. The reaction mixture is concentrated to a volume of about cc. in a stream of air and then diluted to a volume of 40 cc. with Warm water. The solution is cooled and the crystalline D-()-threo-1-p-nitrophenyl- 2 dichloroacetamido 1,3 propanediol (chloramphenicol) collected; M. P. 1501 C.

Example 2 A solution consisting of 0.9 g. of N-acetyl dichloroacetamide and 1.0 g. of DL-threo-l-pnitrophenyl-2-amino-1,3-propanediol in 10 cc. of methanol is heated for five minutes under reflux (temperature about 65-68 C.) and then concentrated to a volume of about 5 cc. by blowing a stream of air over the surface of the reaction mixture. The residue is diluted with cc. of warm water, the solution cooled and the crystalline DL-threo-l-p-nitrophenyl-2-dichloroacetamido 1,3 propanediol (optically racemic chloramphenicol). After recrystallization from ethyl acetate-petroleum ether mixture the product melts at 150 C.

Example 3 A solution consisting of 2.6 g. of dichloroacetamide and 3 g. of D- threo-1-p-nitrop-henyl- 2-dichl0roacetamido-l,3-propanediol in 10 cc. of methanol is heated under reflux (temperature about 65-68 C.) for one hour. During the heating period ammonia is evolved and the reaction mixture becomes dark. The reaction mixture is diluted with water and the solution neutralized with acetic acid. The crystalline D-() -threo- 1 p nitrophenyl 2 dichloroacetamido 1,3- propanediol is collected and purified by recrystallization from hot water with charcoaling; M.P. 150-1 C.

Example 4 2 cc. of a 1 N solution of sodium methylate in anhydrous methanol is added to a solution consisting of 1 g. of DL-threo-1-p-nitrophenyl- 2-amino-l,3-propanediol and 0.82 g. of dichloroacetamide in cc. of anhydrous methanol and the solution heated under reflux for one hour. The reaction mixture is evaporated to a volume of 10 cc. in a stream of air, diluted with 40 cc. of water and extracted with ethyl acetate. The ethyl acetate extract is washed with dilute hydrochloric acid, sodium bicarbonate solution and then with Water. The ethyl acetate solution is dried over magnesium sulfate and the ethyl acetate distilled to obtain the desired DL-threo- 1 p nitrophenyl 2 dichloroacetamido 1,3- propanediol; M. P. 150 C.

Example 5 A solution consisting of 2.3 g. of N-benzoyl dichloroacetamide and 2.1 g. of D-(-)-threol p nitrophenyl 2 amino 1,3 propanediol in cc. of methanol is heated at C. for onehalf hour. The reaction mixture is concentrated to a volume of about 10 cc. in a stream of air and diluted to a volume of 40 cc. with warm water. The solution is allowed to cool and the crystalline D -threo 1 p nitrophenyl- 2 dichloroacetamido 1,3 propanediol collected and purified by recrystallization from water; M. P. 151 C.

Example 6 A solution consisting of 1.9 g. of N-butyryl dichloroacetamide and 2.1 g. of L-(+) -threo- 1 p nitrophenyl 2 amino 1,3 propanediol in 20 cc. of ethanol is allowed to stand at room temperature for about one and one-half hours. The reaction mixture is concentrated to dryness in a stream of air and the residue taken up in cc. of hot water. The aqueous solution is cooled and the crystalline L-(+)-threo-1 p nitrophenyl-2-dichloroacetamido-1,3-propane collected; M. P. 150-1 C.

Example 7 A mixture consisting of 2.5 g. of N-dichloroacetyl dichloroacetamide and 2.1 g. of DL-threol-p-nitrophenyl-Z-amino-1,3-propanediol in cc. of water is heated to boiling and the resulting solution allowed to cool. (During the heating period solution of the reactants becomes complete at about 65 C.) The crystalline DL- threo 1 p-nitrophenyl 2 dichloroacetamido- 1,3-propanediol is collected and dried; M. P. 150 C.

Example 8 A mixture consisting of 2.5 g. of N-dichloroacetyl dichloroacetamide and 2.1 g. of D-(-)- threo 1- p nitrophenyl 2 amino 1,3 propanediol and 75 cc. of 50% aqueous methanol I v is stirred at room temperature for one hour.

Most of the methanol is removed from the re action mixture by distillation in vacuo and the aqueous residue heated until the solids dissolve. The D threo l p nitrophenyl 2- dichloroacetamido-1,3-propanediol which separates on cooling is collected and dried; M. P. -1 C.

Example 9 A solution consisting of 2.5 g. of N-dichloroacetyl dichloroacetamide and 2.1 g. of BL- erythro 1 p nitrophenyl 2 amino 1,3- propanediol in 20 cc. of methanol is warmed at 50 C. for ten minutes. The reaction mixture is concentrated to a volume of 10 cc. in a stream of air and diluted to a volume of 40 cc. with warm water. The solution is cooled and the crystalline DL erythro 1 p nitrophenyl-' 2 dichloroacetamido 1,3 propanediol collected and dried; M. P. l69-'70 C.

Example 10 1. Process for the production of a l-p-nitro-. phenyl 2 dichloroacetamido 1,3 propanediol of formula,

NOOJJH-JJEL-OEOH which comprises reacting at a temperature below 100 C. a 1-p-nitrophenyl-2-amino-1,3-propanediol of formula,

OH NH:

with an acylating agent having the formula R-NHCOCHClz where R is a member of the class consisting of hydrogen and carboxylic acid acyl.

2. Process for the production of a 1p-nitrophenyl 2 dichloroacetamido 1,3 propanediol of formula,

I Noz-Oc11-oHomoH yl-2-amino-1,3-propanediol with N-acetyl dichloroacetamide.

5. Process for the production of optically racemic chloramphenicol which comprises reacting at a temperature below 100 C. DL-threo- 1 p nitrophenyl 2 amino 1,3 propanediol with N -dichloroacetyl dichloroacetamide.

6. Process for the production of optically racemic chloramphenicol which comprises reacting at a temperature below 100 C. DL-threo-lp-nitrophenyl-z-amino-1,3-propanediol with N- acetyl dichloroacetamide.

7. Process for the production of chloramphenicol which comprises heating D-()-threo-1-pnitropheny1-2-amino-1,3-propanedio1 with dichloroacetamide at a temperature of to C.

8. Process for the production of a l-p-nitrophenyl 2 dichloroacetamido 1,3-propanediol of formula,

which comprises reacting at a temperature below C. a. l-p-nitrophenyl-Z-amino-1,3-propanediol of formula,

OH NH:

with an acylating agent having the formula acyl-NHCOCHClz where acyl is halogen substituted lower fatty acid acyl.

9. Process for the production of chloramphenicol which comprises heating to a temperature about 65 C. a methanol solution containing N- dichloroacetyl dichloroacetamide and D-()- threo 1 p nitrophenyl 2 amino 1,3 propanediol, concentrating the methanol solution, diluting with water, cooling and collecting from the aqueous methanol solution crystallized chloramphenicol.

References Cited in the file of this patent UNITED STATES PATENTS Name Date Crooks et a1. Oct. 4, 1949 Crooks et a1 Jan. 23, 1951 OTHER REFERENCES Degering: An Outline of Organic Nitrogen Compounds (1945), p. 409.

Galat et al.: J. Am. Chem. 800.. vol. 65 (1943). pp. 1566-67.

Number 

1. PROCESS FOR THE PRODUCTION OF A 1-P-NITROPHENYL - 2 - DICHLOROACETAMIDO - 1,3 - PROPANEDIOL OF FORMULA, 